I've been unsuccessful with a Natty upgrade, in this sense: I'm unable to use anything but a Metacity theme ("Ubuntu Classic (No effects)"). So I lost all my Compiz effects, the most valuable of which, for me, was the grid layout tool. I think the problem is confused Radeon/ATI driver issues -- fglrx was dead on arrival with the update, and falling back to the generic ATI driver gets me Metacity but not Compiz.
I'm now considering preserving my /home directory and doing a clean install of Natty on my system drive. Unity works decently well on a USB drive boot -- not that I'm especially fond of it, but I want to give it a fair shake. Presumably it will work with a clean install.
But I'm frankly concerned about all the hidden gnome and X configuration files in my restored home directory. When I plop my old homedir onto a new 11.04 system install with all my old packages, what's going to happen?
(amd64, RV710 Radeon HD 4550, dual monitors)